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Search Results: 1 - 10 of 10083 matches for " Kyung-Woo Park "
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Efficacies of the new Paclitaxel-eluting Coroflex Please? Stent in percutaneous coronary intervention; comparison of efficacy between Coroflex Please? and Taxus? (ECO-PLEASANT) trial: study rationale and design
Jae-Bin Seo, Hui-Kyung Jeon, Kyung-Woo Park, Jong-Seon Park, Jang-Ho Bae, Sang-Wook Kim, Keon-Woong Moon, Jae-Woong Choi, Sang-Gon Lee, Woo-Young Chung, Tae-Jin Youn, Soo-Joong Kim, Doo-Il Kim, Byung-Ok Kim, Min-Su Hyon, Keum-Soo Park, Tae-Joon Cha, Hweung-Kon Hwang, Seung-Ho Hur, Hyo-Soo Kim
Trials , 2009, DOI: 10.1186/1745-6215-10-98
Abstract: In the comparison of Efficacy between COroflex PLEASe? ANd Taxus? stent(ECO-PLEASANT) trial, approximately 900 patients are being prospectively and randomly assigned to the either type of Coroflex Please? stent and Taxus Liberte? stent via web-based randomization. The primary endpoint is clinically driven target vessel revascularization at 9 months. The secondary endpoints include major cardiac adverse events, target vessel failure, stent thrombosis and angiographic efficacy endpoints.The ECO-PLEASANT trial is the study not yet performed to directly compare the efficacy and safety of the Coroflex Please? versus Taxus Liberte? stent. On the basis of this trial, we will be able to find out whether the Coroflex Please? stent is non-inferior to Taxus Liberte? stent or not.ClinicalTrials.gov number, NCT00699543.Previous randomized trials have shown the efficacy of a slow-release polymeric sirolimus-eluting stent (Cypher?, Cordis, Warren, NJ, USA), paclitaxel-eluting stent (Taxus?, Boston Scientific, Natick, MA, USA), and zotarolimus-eluting stent (Endeavor?, Medtronic, Minneapolis, MN, USA) over bare metal stents in reducing neointimal hyperplasia, late luminal loss, and angiographic restenosis leading to decreased target lesion revascularization [1-11] The Paclitaxel-eluting Coroflex Please? stent is a newly developed drug eluting stent using the Coroflex? stent platform combined with the drug paclitaxel contained in a polymer coating[12]In the PECOPS I, which was one-arm observational study, the results of Coroflex Please? stent were within the range of other Paclitaxel-eluting coronary stents [12,13] Compared with binary restenosis rate of 7.9% in Taxus IV trial, Coroflex? Please stent showed 7.8% of restenosis rate[7] The 3.1% of 30 day MACE rate is within the range of other trials with stents eluting Paclitaxel or Sirolimus. The 6 month MACE rates in PECOPS I were 8.0%, which was similar to 7.8%, and 8.5% in Taxus II MR and SR, respectively[6] In Taxus IV, 9 month f
Numerical Study on the Effects of Contraction Ratio in a Two-Phase Flow Injection Nozzle  [PDF]
Haider Ali, Kyung Won Kim, Jae Sik Kim, Jong Yun Choi, Cheol Woo Park
Open Journal of Fluid Dynamics (OJFD) , 2016, DOI: 10.4236/ojfd.2016.61001
Abstract: The Euler-Euler numerical method was used to investigate the effects of contraction ratio on twophase flow mixing with mass transfer in the flow injection nozzle. The geometric shape of the nozzle was modified to improve carbonation efficiency. A gas inlet hole was created to increase the flow mixing of CO2 with water. A nozzle throat was also introduced to increase the gas dissolution by increasing flow rates. Various contraction ratios of nozzle throat, inlet gas and liquid velocities, and gas bubble sizes were employed to determine their effects on gas hold-up, gas concentration, and mass transfer coefficient. Results revealed that the flow injection nozzle with high contraction ratios improved carbonation because of high gas hold-up. Gas concentration was directly related to contraction ratio and gas flow velocities. Carbonation reduced when high liquid velocities and large gas bubbles were employed because of inefficient flow mixing. This study indicated that flow injection nozzle with large contraction ratios were suitable for carbonation because of their ability to increase gas hold-up, gas concentration, and mass transfer coefficient.
Cognitive Profiles and Subtypes of Patients with Mild Cognitive Impairment: Data from a Clinical Follow-Up Study  [PDF]
Kyung Won Park, Eun-Joo Kim, Hwan Joo, Sung-Man Jeon, Seong-Ho Choi, Jay C. Kwon, Byoung Gwon Kim, Jae Woo Kim
International Journal of Clinical Medicine (IJCM) , 2012, DOI: 10.4236/ijcm.2012.35068
Abstract: Background: Mild cognitive impairment (MCI) is a heterogeneous condition with a variety of clinical outcomes, the presence of which correlates with risk of Alzheimer’s disease as well as pre-clinical stages of other dementia subtypes. The aims of this study were to assess the specific patterns of cognitive profiles and to identify changes from baseline to 24 weeks in patients with MCI using detailed neuropsychological testing. Methods: We consecutively recruited 120 MCI patients at baseline according to the Petersen’s clinical diagnostic criteria, who were admitted to the Dementia and Memory Clinics. We analyzed patients who fulfilled both inclusion and exclusion criteria for MCI and classified them into four subtypes according to deficits in major cognitive domains; amnestic MCI single domain (aMCI-s), amnestic multiple domain MCI (aMCI-m), non-amnestic single domain MCI (naMCI-s) and non-amnestic multiple domain MCI (naMCI-m). Four groups of MCI were evaluated by a detailed neuropsychological battery test. Results: 83 patients with MCI at the 24-week follow-up were classified into four subtypes. The most frequent subtype was amnestic multi-domain MCI, with the frequency of MCI subtypes as follows: aMCI-s (n = 21, 25.3%), aMCI-m (n = 53, 63.9%), naMCI-s (n = 5, 6.0%) and naMCI-m (n = 4, 4.8%). In the major cognitive items of the SNSB-D, there were significant changes between the initial and follow-up tests in the domains of language, memory and the fron-tal/executive function (p < 0.05), except for attention, in all MCI patient subtypes. At 24-weeks follow-up, the conversion rate to Alzheimer’s disease was 2.4% (n = 2) from a subtype of amnestic multi-domain MCI. Conclusions: Our study revealed the most frequent subtype of MCI to be multiple domain amnestic MCI, with this subtype having a higher tendency of conversion to Alzheimer’s disease.
Large-Scale Production of Microalgal Lipids Containing High Levels of Docosahexaenoic Acid upon Fermentation of Aurantiochytrium sp. KRS101  [PDF]
Won-Kyung Hong, Anna Yu, Baek-Rock Oh, Jang Min Park, Chul Ho Kim, Jung-Hoon Sohn, Akihiko Kondo, Jeong-Woo Seo
Food and Nutrition Sciences (FNS) , 2013, DOI: 10.4236/fns.2013.49A1001
Abstract:

In this study, large-scale production of microalgal lipid containing high levels of docosahexaenoic acid (DHA) by fermentation of Aurantiochytrium sp. KRS101 was performed. The microalgal strain yielded productivity of docosahex-aenoic acid (DHA) productivity of 1.08 and 1.6 g/L/d by fermentation at 300-L and 5000-L scale stirrer-type bioreactor. The productivity was significantly enhanced upto 5.6 g/L/d by fermentation at 6000-L scale airlift-type bioreactor, probably due to the reduced shearing force. The microalgal lipid could be efficiently recovered by safe extraction methods such as ethanol extraction, hot water extraction or supercritical fluid extraction, promising commercial potential of the microalgal DHA-rich lipid in the food and feed industry.

Understanding of Ultrasonic Assisted Machining with Diamond Grinding Tool  [PDF]
Kyung-Hee Park, Yun-Hyuck Hong, Kyeong-Tae Kim, Seok-Woo Lee, Hon-Zong Choi, Young-Jae Choi
Modern Mechanical Engineering (MME) , 2014, DOI: 10.4236/mme.2014.41001
Abstract:

In this work, machining test was carried out in various machining conditions using ultrasonic vibration capable CNC machine. For work material, alumina ceramic (Al2O3) was used while for tool material diamond electroplated grinding wheel was used. To evaluate ultrasonic vibration effect, grinding test was performed with and without ultrasonic vibration in same machining condition. In ultrasonic mode, ultrasonic vibration of 20 kHz was generated by HSK 63 ultrasonic actuator. On the other hand, grinding forces were measured by KISTLER dynamometer. And an optimal sampling rate for grinding force measurement was obtained by a signal processing and frequency analysis. The surface roughness of the ceramic was also measured by using stylus type surface roughness instrument and atomic force microscope (AFM). Besides, the scanning electron microscope (SEM) was used for observation of surface integrality.

Antagonist Effects of Veratric Acid against UVB-Induced Cell Damages
Seoung Woo Shin,Eunsun Jung,Seungbeom Kim,Kyung-Eun Lee,Jong-Kyung Youm,Deokhoon Park
Molecules , 2013, DOI: 10.3390/molecules18055405
Abstract: Ultraviolet (UV) radiation induces DNA damage, oxidative stress, and inflammatory processes in human epidermis, resulting in inflammation, photoaging, and photocarcinogenesis. Adequate protection of skin against the harmful effect of UV irradiation is essential. In recent years naturally occurring herbal compounds such as phenolic acids, flavonoids, and high molecular weight polyphenols have gained considerable attention as beneficial protective agents. The simple phenolic veratric acid (VA, 3,4-dimethoxybenzoic acid) is one of the major benzoic acid derivatives from vegetables and fruits and it also occurs naturally in medicinal mushrooms which have been reported to have anti-inflammatory and anti-oxidant activities. However, it has rarely been applied in skin care. This study, therefore, aimed to explore the possible roles of veratric acid in protection against UVB-induced damage in HaCaT cells. Results showed that veratric acid can attenuate cyclobutane pyrimidine dimers (CPDs) formation, glutathione (GSH) depletion and apoptosis induced by UVB. Furthermore, veratric acid had inhibitory effects on the UVB-induced release of the inflammatory mediators such as IL-6 and prostaglandin-E2. We also confirmed the safety and clinical efficacy of veratric acid on human skin. Overall, results demonstrated significant benefits of veratric acid on the protection of keratinocyte against UVB-induced injuries and suggested its potential use in skin photoprotection.
Oscillation Control Algorithms for Resonant Sensors with Applications to Vibratory Gyroscopes
Sungsu Park,Chin-Woo Tan,Haedong Kim,Sung Kyung Hong
Sensors , 2009, DOI: 10.3390/s90805952
Abstract: We present two oscillation control algorithms for resonant sensors such as vibratory gyroscopes. One control algorithm tracks the resonant frequency of the resonator and the other algorithm tunes it to the specified resonant frequency by altering the resonator dynamics. Both algorithms maintain the specified amplitude of oscillations. The stability of each of the control systems is analyzed using the averaging method, and quantitative guidelines are given for selecting the control gains needed to achieve stability. The effects of displacement measurement noise on the accuracy of tracking and estimation of the resonant frequency are also analyzed. The proposed control algorithms are applied to two important problems in a vibratory gyroscope. The first is the leading-following resonator problem in the drive axis of MEMS dual-mass vibratory gyroscope where there is no mechanical linkage between the two proof-masses and the second is the on-line modal frequency matching problem in a general vibratory gyroscope. Simulation results demonstrate that the proposed control algorithms are effective. They ensure the proof-masses to oscillate in an anti-phase manner with the same resonant frequency and oscillation amplitude in a dual-mass gyroscope, and two modal frequencies to match in a general vibratory gyroscope.
Performance Analysis of Radar Target Recognition Using Natural Frequency: Frequency Domain Approach
Joon-Ho Lee;Sung-Woo Cho;Sang-Hong Park;Kyung-Tae Kim
PIER , 2012, DOI: 10.2528/PIER12071107
Abstract: We consider the performance analysis of natural frequency-based radar target recognition in the frequency domain. Based on the probability density function (PDF) of some quantity consisting of the projections of the frequency response onto the column spaces of the matrices constructed using the natural frequencies of the specific targets, we propose to analytically calculate the probability of the correct classification, where the PDF is obtained from the inverse Fourier transform of the characteristic function. The scheme is validated by comparing the performance using the analytic method with that using the Monte-Carlo simulation.
A Method for Assaying Deubiquitinating Enzymes
Lee Jae Il,Woo Seung Kyoon,Kim Keun Il,Park Kyung Chan
Biological Procedures Online , 1998, DOI: 10.1251/bpo11
Abstract: A general method for the assay of deubiquitinating enzymes was described in detail using 125I-labeled ubiquitin-fused &agr;NH-MHISPPEPESEEEEEHYC (referred to as Ub-PESTc) as a substrate. Since the tyrosine residue in the PESTc portion of the fusion protein was almost exclusively radioiodinated under a mild labeling condition, such as using IODO-BEADS, the enzymes could be assayed directly by simple measurement of the radioactivity released into acid soluble products. Using this assay protocol, we could purify six deubiquitinating enzymes from chick skeletal muscle and yeast and compare their specific activities. Since the extracts of E. coli showed little or no activity against the substrate, the assay protocol should be useful for identification and purification of eukaryotic deubiquitinating enzymes cloned and expressed in the cells.
Channel-mediated astrocytic glutamate release via Bestrophin-1 targets synaptic NMDARs
Han Kyung-Seok,Woo Junsung,Park Hyungju,Yoon Bong-June
Molecular Brain , 2013, DOI: 10.1186/1756-6606-6-4
Abstract: Background Astrocytes regulate neuronal excitability and synaptic activity by releasing gliotransmitters such as glutamate. Our recent study demonstrated that astrocytes release glutamate upon GPCR activation via Ca2+ activated anion channel, Bestrophin-1 (Best1). The target of Best1-mediated astrocytic glutamate has been shown to be the neuronal NMDA receptors (NMDAR). However, whether it targets synaptically or extra-synaptically localized NMDAR is not known. Findings We recorded spontaneous miniature excitatory postsynaptic currents (mEPSCs) from CA1 pyramidal cells to test whether Best1-mediated astrocytic glutamate targets synaptic NMDAR. An agonist of protease activated receptor 1 (PAR1) was used to induce astrocytic Ca2+ increase and glutamate release. Firstly, we found that activation of PAR1 and subsequent release of glutamate from astrocyte does not alone increase the frequency of mEPSCs. Secondly, we found that mEPSC rise time is variable depending on the different electrotonic distances from the somatic recording site to the synaptic region where each mEPSC occurs. Two subgroups of mEPSC from CA1 pyramidal neuron by rise time were selected and analyzed. One group is fast rising mEPSCs with a rise time of 1 ~ 5 ms, representing synaptic activities arising from proximal dendrites. The other group is slowly rising mEPSCs with a rise time of 5 ~ 10 ms, representing synaptic events arising from glutamate release at synapses located in the distal dendrites. We used cell-type specific Best1 gene silencing system by Cre-loxP cleavage to dissociate the effect of neuronal and astrocytic Best1. Astrocytic Best1-mediated glutamate release by PAR1 activation did not affect decay kinetics, frequency, and amplitude of fast rising mEPSC. In contrast, PAR1 activation resulted in an NMDA receptor component to be present on slowly rising mEPSC, but did not alter frequency or amplitude. Conclusions Our results indicate that astrocytic glutamate via Best1 channel targets and activates synaptic NMDARs.
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